Motorola SVG2500 manual Term Definition TTL, Term Definition UDP, Usb, Utp, Vlan

17 GLOSSARY
TERM	DEFINITION
TTL	The time to live is the number of routers (or hops) a packet can
	traverse before being discarded. When a router processes a
	packet, it decreases the TTL by 1. When the TTL reaches zero,
	the packet is discarded.
tunnel	To place packets inside other packets to send over a network.
	The protocol of the enclosing packet is understood by each
	endpoint, or tunnel interface, where the packet enters and
	exits on the network. VPNs rely on tunneling to create a secure
	network.
	Tunneling requires the following protocol types:
	• A carrier protocol, such as TCP, used by the network that
	the data travels over
	• An encapsulating protocol, such as IPSec, L2F, L2TP, or
	PPTP, that is wrapped around the original data
	• A passenger protocol, such as IP, for the original data
two-way	A cable system that can transmit signals in both directions to
	and from the headend and the subscriber.

U-Z

TERM	DEFINITION
UDP	User Datagram Protocol
unicast	A point-to-point data transmission sent from one sender to one
	receiver. This is the normal way you access websites. See also
	broadcast and multicast
upstream	In a cable data network, upstream describes the direction of data
	sent from the subscriber’s computer through the cable modem
	to the CMTS and the Internet.
USB	Universal Serial Bus is a computer interface for add-on devices
	such as printers, scanners, mice, modems, or keyboards. USB
	supports data transfer rates of 12 Mbps and plug-and-play
	installation. You can connect up to 127 devices to a single USB
	port.
UTP	Unshielded twisted pair (wire)
VLAN	A virtual local area network is group of devices on different LAN
	segments that are logically configured to communicate as if
	they are connected to the same wire.
VoIP	Voice over Internet Protocol is a method to exchange voice,
	fax, and other information over the Internet. Voice and fax have
	traditionally been carried over traditional telephone lines of the
	PSTN using a dedicated circuit for each line. VoIP enables calls
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